The biggest disadvantage with summer time for me is the shortened hours of darkness. Spring to early summer brings the winds, which seem to be so much stronger on top of the divide here. So I suppose I lean towards Autumn and Winter even if sub zero temps are the norm.
I think I have the warm clothing sorted out for cold nights - thermals, jeans and shirt, thick socks, fingerless woolen gloves and beanie, a throat coat and a windstopper jacket... then if it's really cold, a freezer jacket and pants over the top! I have managed to work up a sweat standing perfectly still for an hour or two while forming icicles on the back of my OTA with my breath...
Al.